As set forth in DE 103 42 037 A1, hydraulic systems in which a plurality of consumers are supplied with pressure medium via a variable displacement pump are used, especially in mobile hydraulics, to activate these consumers. A metering orifice and a pressure compensator are provided between the variable displacement pump and each consumer, it being possible for the pressure compensator to be connected upstream or downstream of the metering orifice. In this case a distinction is made between LS (load sensing) systems operating on the flow regulation principle and systems operating on the flow distribution principle. In the latter, the pressure compensator is connected downstream of the metering orifice. These flow distribution systems are also referred to as LUDV (load-independent flow distribution) systems, which form a subgroup of the LS systems, in which the highest load pressure of the hydraulic consumers is communicated to a pump which is controlled in such a way that a pump pressure higher by a predetermined pressure difference than the highest load pressure is applied in the pump line. In an LUDV control arrangement, as described, for example, in DE 10 2005 033 222 A1, the pressure medium volume flow to the respective consumer is set by means of adjustable supply metering orifices each having an associated individual pressure compensator, by means of which the pressure drop across the respective supply metering orifice can be maintained constant.
In the LUDV control system the individual pressure compensators are arranged downstream of the metering orifices and in each case throttle the pressure medium volume flow between the metering orifice and the load by an amount such that the pressure to all metering orifices is equal, preferably equal to or slightly above the highest load pressure. The pump pressure is applied equally upstream of all the metering orifices, so that the pressure difference changes in the same way at all the metering orifices if the pump pressure decreases in the event of undersupply. In this case the distribution of the pressure medium volume flow (flow distribution principle) between the supply metering orifices of the activated consumers is maintained.
In the aforedescribed LS/LUDV architectures, the variable displacement pump is activated in dependence on the highest load pressure tapped via an LS line in such a way that a pressure higher than the highest load pressure by a pressure difference equivalent to the force of a control spring of a pump regulating valve is established in the pump line.
In DE 103 42 037 A1 a so-called EFM (Electronic Flow Matching) architecture is explained, whereby actuation signals are output to a pump regulating valve of the variable displacement pump as a function of reference values predefined, for example, by means of a joystick, in order to adjust the pressure medium volume flow.
A problem with such architectures implemented in mobile hydraulics is that the valves present for controlling the pressure medium volume flows are usually combined in one control block which is housed, in an excavator for example, in the region of the revolving superstructure. The pressure medium connection to the respective consumer is effected via at least one supply and return line per consumer. These lines, together with the corresponding brackets and screw connections, represent a considerable proportion of the total system costs.
In contrast, it is the object of the disclosure to reduce the equipment-related outlay for implementing a hydraulic control arrangement, and to provide a simplified method for activating a plurality of consumers.
This object is achieved, with regard to the control arrangement and the method described herein.